One vertex per element, one color per generator, with an edge from x to x·s.
(1,2,4,6)(3,5,7,8)(9,10,13,16)(11,12,15,14)(19,23)(22,24)(26,30)(27,33)(32,36)(35,39)(9,11)(10,14)(12,16)(13,15)(18,21)(22,24)(25,26,29,30)(27,31,33,34)(28,32,37,36)(35,38,39,40)(11,15)(12,14)(17,18,20,21)(19,22,23,24)(25,26)(27,34)(28,36)(29,30)(31,33)(32,37)(35,38)(39,40)(1,2)(3,5)(4,6)(7,8)(9,10)(11,14)(12,15)(13,16)(17,19)(18,22)(20,23)(21,24)(25,27)(26,31)(28,35)(29,33)(30,34)(32,38)(36,40)(37,39) involution — undirected(1,3,4,7)(2,5,6,8)(9,12,13,14)(10,15,16,11)(17,19)(18,22)(20,23)(21,24)(25,28)(26,32)(27,35)(29,37)(30,36)(31,38)(33,39)(34,40)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.